This invention relates to an electrographic apparatus comprising a photosensitive drum composed of a foil-shaped photosensitive body wound around a pair of disc-shaped frames and a corona discharge device arranged in the photosensitive drum and emitting a flow of corona ions toward the photosensitive drum.
An electrographic apparatus has been proposed which makes use of a foil-shaped photosensitive body of four layers construction comprising an electrically conductive substrate having a number of openings, a photosensitive layer coated on one side of the substrate, an insulating layer coated on the other side of the substrate and an electrically conductive layer coated on the insulating layer, and in which the photosensitive body is uniformly charged, then is exposed to a light image of a manuscript to be copied so as to produce, on the foil-shaped photosensitive body, a first electrostatic latent image corresponding to the manuscript image and subsequently a flow of corona ions is modulated on the basis of the first electrostatic latent image so as to transfer, onto an electrostatic record sheet, a second electrostatic latent image corresponding to the first electrostatic latent image. The second electrostatic latent image produced on the electrostatic record sheet is developed and fixed to obtain a visible image. This apparatus is capable of controlling each of successive steps in any suitable manner by adjusting a bias voltage applied between the electrically conductive substrate and the electrically conductive layer of the foil-shaped photosensitive body, and hence is significantly useful in practice.
In such electrographic apparatus, the foil-shaped photosensitive body is often composed of a drum-shaped body for the purpose of making the copying speed high and making the apparatus compact in construction.
In an electrographic apparatus which makes use of a photosensitive drum composed of a foil-shaped phototsensitive body, it is desirous to construct the apparatus such that the photosensitive drum and the corona discharge device can be removed from the apparatus for the purpose of replacing or cleaning the foil-shaped photosensitive body and the corona discharge device. Such method of removing the photosensitive drum and the corona discharge device from the apparatus is mainly divided into a method of pulling out the photosensitive drum and the corona discharge device in an axial direction of the drum and another method of removing the photosensitive drum and the corona discharge device in a direction for feeding a record sheet to be copied. In general, the former method of pulling out the photosensitive drum and the corona discharge device in the axial direction of the drum is simple in construction.